1. Technical Field
The present invention relates to a surface mount crystal oscillator with a pedestal (hereunder, referred to as “oscillator with a pedestal”), and in particular to an oscillator with a pedestal that enables easy attachment of a pedestal to a crystal oscillator.
2. Background Art
Crystal oscillators that serve as frequency control devices used for mobile communication devices or transmission communication devices, are well known. As one of these crystal oscillators, there has been widely used a lead-type crystal oscillator in which lead wires are perpendicularly implanted in the bottom surface of the oscillator. On the other hand, while surface mounting of electronic components has made progress, there has also been a demand to be able to surface mount a crystal oscillator. Under such a background, there has been proposed a crystal oscillator with a pedestal in which a pedestal is attached on an existing lead-type crystal oscillator thereby enabling surface mounting thereof (refer to Japanese Unexamined Patent Publication No. 2000-286661 (Patent Document 1)).
3. Prior Art
FIG. 6 and FIG. 7 are drawings for describing an oscillator with a pedestal of a conventional example, wherein FIG. 6A is a front view thereof, FIG. 6B is a bottom view thereof, and FIG. 6C is a sectional view thereof taken along the line VI-VI of FIG. 6B. FIG. 7 is an exploded isometric view of a pedestal of the conventional example, wherein FIG. 7A shows an exploded view of a first substrate and FIG. 7B shows an exploded view of a second substrate.
Here, there is described an oscillator with a pedestal disclosed in Japanese Unexamined Patent Publication No. 2006-332932 (Patent Document 2). Although it is described as a crystal resonator with a pedestal in this Patent Document 2, a similar configuration can be applied to a crystal oscillator with a pedestal, and therefore it is described here as a crystal oscillator with a pedestal.
In this crystal oscillator with a pedestal, a pedestal 2 is attached to a crystal oscillator 1 as shown in FIG. 6A to FIG. 6C. The crystal oscillator 1 is configured with a crystal resonator (not shown in the drawing) and an oscillation circuit element (not shown in the drawing) housed (enclosed) inside a metallic base 3, and a metallic cover 4 joined thereon. On an outer bottom surface 3a of the metallic base 3 of the crystal oscillator 1, there are provided stand-offs 5, thereby preventing electrical short circuit between a mounting substrate (not shown in the drawing) and the metallic base 3, when the crystal oscillator 1 is directly mounted on the mounting substrate. On the outer bottom surface 3a of the crystal oscillator 1, there are implanted four lead wires 6 perpendicular to the outer bottom surface 3a. The lead wires 6 are electrically connected to the oscillation circuit element and the like housed in the metallic base 3.
Next, the pedestal 2 comprises a laminated plate comprising a first substrate 7 serving as an upper layer and a second substrate 8 serving as a lower layer. Moreover, the pedestal 2 has insertion holes 9a and 9b in portions thereof corresponding to the lead wires 6. Here, the radius of the insertion hole 9b formed in the second substrate 8 is made greater than the radius of the insertion hole 9a of the first substrate 7 (refer to FIG. 7A and FIG. 7B). Moreover, each of the lead wires 6 passes through each of the insertion holes 9a of the first substrate 7. On the inner side surface of each insertion hole 9a, there is formed a metallic film that serves as a conducting path 10a (refer to FIG. 6C).
On the outer periphery of the insertion hole 9a on the lamination surface of the first substrate 7 that is to have the second substrate 8 laminated thereon, as shown in FIG. 6C, there is formed a terminal electrode 11, and on a bottom surface 8a of the second substrate 8 that serves as the bottom surface of the pedestal 2, there are formed mount terminals 12. The lead wire 6 having passed through the insertion hole 9a is electrically connected to the terminal electrode 11 by means of solder 13. Moreover, the solder 13 also flows into the insertion hole 9a, and consequently the lead wire 6 is electrically and mechanically connected to the conducting path 10a. As a result, the lead wire 6 is electrically connected to the mount terminal 12 via; the terminal electrode 11 and the conducting path 10a, a conducting path 10b formed on a surface 7a of the first substrate 7 facing the crystal oscillator 1, and a conducting path 10c formed on the side surface of the pedestal 2.